On Mon, 26 Nov 2007 20:34:38 +0900, Tejun Heo wrote:
> Make pdc_atapi_pkt() use values from qc->tf instead of creating its
> own. This is to ease future ATAPI handling changes.
>
> DONT APPLY YET
> ---
> Mikael, would this work? Values other than lbam and lbah remain the
> same. Does sata_promise have strict requirements for lbam and lbah?
...
> /* set feature and byte counter registers */
> - if (qc->tf.protocol != ATA_PROT_ATAPI_DMA) {
> + if (qc->tf.protocol != ATA_PROT_ATAPI_DMA)
> feature = PDC_FEATURE_ATAPI_PIO;
> - /* set byte counter register to real transfer byte count */
> - nbytes = qc->nbytes;
> - if (nbytes > 0xffff)
> - nbytes = 0xffff;
> - } else {
> + else
> feature = PDC_FEATURE_ATAPI_DMA;
> - /* set byte counter register to 0 */
> - nbytes = 0;
> - }
> +
> buf[20] = (1 << 5) | ATA_REG_FEATURE;
> buf[21] = feature;
> buf[22] = (1 << 5) | ATA_REG_BYTEL;
> - buf[23] = nbytes & 0xFF;
> + buf[23] = qc->tf.lbam;
> buf[24] = (1 << 5) | ATA_REG_BYTEH;
> - buf[25] = (nbytes >> 8) & 0xFF;
> + buf[25] = qc->tf.lbah;
The original code matches what Promise' own driver does, including
the "set byte counter register to real transfer byte count" comment.
It's certainly possible that if lbah/lbam don't match ->nbytes,
the HW will go nuts. Their data sheets are very quiet about ATAPI.
I can test your proposed change next weekend when I'm back to where
my sata_promise test equipment is.
/Mikael
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